Straying from tradition – soundboards

[James Mc]

Hi All
I’ve been tempted to stray from tradition in the one area I didn’t think I was ever likely to do so, the soundboard. I recently threw in an impulse bid on some King William Pine that Barry was selling on ebay and ended up getting it. I didn’t really have any plan for using it except for maybe as an interesting soundboard on a harp. But when I unwrapped it I was instantly enamoured by both the look and feel of it, so decided to glue on a couple of wings to get the width I need to and give it a go on the Huon pine flamenco I’m working on. The grain isn’t very straight but is well enough quartered on the main working part of the top so I’m not too concerned.

This got me to wondering how far you could go using less than well quartered top woods with the odd flaw (or fifty). I’m very tempted to use the offcuts from the more figured part of the boards on a little steel string.

The question is how much would it hurt the sound to do so???

Couple of pics… Top is half the top for the flamenco and below is the bit I’m thinking about using for a small steel string.

P.S. The strange little knots are totally sound and not much harder than the timber.

[kiwigeo]

Dunno mate..there are some pretty healthy looking knots happening.

Ive got some Huon in my shop but its cut on the quarter and knot free.

Give it a go if youve got nothing else planned for the wood and you never know you might get a surprise.

Cheers Martin

[joel Thompson]

straying from quarter sawn will loose you stiffness first and formost which would mean you would have to use a thicker top which would defeat the purpose of using lightweight stiff wood for the top.

the top is under so much presure you need as much strength and stability as possable anything, other than quarter sawn wood will cuase real problems.

have you held a spruce top that has even grain spacing and is perfectly quarter sawn for the first half and runs just a little (say 2 degrees) off quarter for the rest of the top.
The off quarter side will be noticable floppy compared to the perfect quartered side.

in soft wood tops its very impotant impotant that the wood be as close to bang on quarter as poss or you will loose stiffness.

i dont know about aussy woods but i wuld presume its the same principle.

as for hardwoods again stiffness is an issue but you will get uneven bellying if you your top runs off the quarter at the edges due to uneaven stresses in the wood.

Joel.

[kiwigeo]

The way I see it youve got three choices:

1. play conservative and avoid using the wood.
2. go ahead and use the wood and either be surprised or verify for yourself what others are saying about using top wood not cut on the quarter. I know of at least a couple of archtops with slab sawn tops but I dont know of any conventional acoustics. If youve got the time Id certainly like to see how you go. If the instrument is a dud then read taffy's tutorial on changing out a top on a Maton and get some valuable practise in guitar repair.....always a good thing IMO.
3. give the wood a coat of KBP coloured paint and then carefully paint a nice parallel grain on it and then flog it to Kim as a master grade top.

Cheers Martin

[Dave White]

James,

If it were me I'd use it for a steel string and use it as an interesting learning exercise in using all the other elements of instrument design to coax out the best sound from a less than "conventionally perfect" top. There are lots of ways that you can bring stiffness back to a floppy top (now there's a potential new Aussie euphamism ). Extra thickness - especially in the centre - is not all bad news, especially if you like good mids and trebles. Put more arching into the top than you usually would for example.

Then make one with a perfectly quartersawn top and see how much better you can make the sound.

Doing things differently from conventional wisdom will usually give you one of two results - a confirmation of the wisdom, or interesting discoveries that take your building into new and interesting areas.

[Paul B]

Go for it dude!

It'll be interesting.

Interesting 'cause I bought some king billy sound boards from Barry a couple years ago and one of them isn't all that well quartered so I'll be interested to see how yours go.

[graham mcdonald]

A couple of things to consider. King Billy is not spruce, and has to be used quite differently. I would add 20-25% in thickness to what you would use for a similar spruce soundboard, unless you are going the lattice/carbonfiber route. A too-thin King Billy soundboard will just sound tubby. Thickness it to 3mm and compare the tap to a 2-2.5mm spruce top. That will give you some reference point and help your decisions about whether to continue with it. If it is roughly in the same range that will suggest that you can do with it what you might do with a spruce top. If not, perhaps some rethinking.

The swirly grain may or may not be a problem, but it will make it fun cutting the rosette groove. I think you will want a Dremel or other router setup.

At worst, you can always remove the top and replace it. Don't be seduced by all the waffle that gets written about having to have the perfect materials for every instrument. Very good instruments can be made with what often gets dismissed as inferior A or AA grade timber and having an understanding of the material. It doesn't have to be AAAA grade wood. I suspect there are lots of guitars being made out there with really choice materials that are little more than good carpentry.

cheers

graham

[Paul B]

So Graham, Would you go with tap tone over just flexing it/deflection testing?

I was thinking that I'd thickness mine by comparing the deflection against a spruce top that was a partner to one I'd used on a guitar of the same type (that turned out well ). That'd have to be pretty close yeah? Or, am I missing something important?

Either that or just cut off the off-quarter bits and use a perfectly quartered King Billy top for a mando or three. There is some appeal there...

Man, I gotta buy that book! Maybe next month

[kiwigeo]

A couple of things to consider.

Ghost who walks in his underpants has spoken.

[kiwigeo]

I suspect there are lots of guitars being made out there with really choice materials that are little more than good carpentry.

That underpansty Phantom man has been in my bldi workshop.....

[James Mc]

Yep, have decided to try it and if it doesn’t work then I’ll change out the top to spruce. The gift I give to any kid I work with that owns a cheap laminated top guitar and looks like they will keep playing is to replace the top with a solid one (I had a bunch of B tops I got for $5 each from Canada that turned out to be as good or better than a AAA top I got from a luthier shop… only a few left now). It is amazing how much better a budget guitar can sound with just a top replacement. What this has given me apart from happy inspired kids… is a heap of practice at replacing tops. My tip for anyone replacing tops is to buy a cheap electric soldering iron from bunnies or super cheap and forge the tip down to a nice flat little knife. I run this from a lead that has a built in light dimmer switch so it doesn’t get over hot, but it doesn’t seem to get so hot that it is a problem to use it without. I’m never looking to salvage the old top so I just remove the fretboard then cut out the top a bit in from the side with a jigsaw, makes it much easier to remove the binding and get the rest of the top of using a hot knife and heat gun.

Back to the King William Pine… I only build for fun so tapping the timber isn’t probably the best option for me (still haven’t penetrated the mystery of tap tone). I’ve taken a bit of WRC, Sitka and a bit of both the quartered and non-quartered KBP down to about 3.5mm to compare stiffness across and along the grain.

Just going by feel (no science involved) the quartered KBP is about a third stiffer across the grain than the non-quartered but the non-quartered seems a little stiffer along the grain. As is to be expected the bits of KBP are far stiffer across the grain than the WRC (which is like a wet noodle). Doesn’t seem to be much difference in stiffness between the WRC and KBP along the grain. The spruce and KBP are much closer, the quartered KBP is a little easier to flex along the grain and a little stiffer across it. The non-quartered is very close to the sitka in both directions. When I tap a half top of each that are about the same size, the WRC is quieter with more ring than the sitka and the KBP falls somewhere in the middle (and none of them come close to lovely sound from tapping a bit of quartered Aust Red Cedar). I’ll try and find some time over the weekend to do something a bit more scientific.

[graham mcdonald]

Ghost who walks in his underpants has spoken.

You just watch out Martin, or there will be Bandar pygmies in the shrubberies.

Another thing to consider about that bit of KB is that the grain swirliness does mean that planing a centre join could also be tricky, as it is getting very close to endgrain at some points. That could also effect the gluing.

I don't think you have to do anything fancy about testing. Hold the wood about the 10 o'clock position, tap around the 4 o'clock. Move holding fingers and tapping finger until a clear(ish) note is heard. Work out what that note is with a tuner, or a computer and you have the basic vibrational mode of that plate (or at least the one that is most use to guitar builders). If you have a piece of spruce of what you think is a decent quality, thicknessed down to usual working thickness and it goes 'bong' at a particular frequency when tapped, if the piece of KB can be made to go 'bong' at more or less the same frequency (regardless of thickness) then it is going to hopefully act as a guitar top in a similar way. It may well feel differently when flexed, and excessive floppiness across the grain means thinking about adding some stiffness with the bracing.

cheers